Magnetic fluid variable torque wrench



April 24, 1956 e. R. NELSON 2,742,805

MAGNETIC FLUID VARIABLE TORQUE WRENCH Filed Jan. 8, 1954 INVENTOR.

Gar/nan f? lVe/son RNEY United States Patent MAGNETIC TORQUEiWRE'NCIl "'GomianlRe Nelson, Siouxiialls', S.1.Dak. Application January 8, 1954,. Serial-No.= 402,865

- S GIaims- (CL '8-1"52.4)

2,742,805 Patented Apr. 24, 1956 27 to a -,further magnetic --cy1indricalmember -28 which isdntegtallY-formed with the further disk-member 29 ..My:. inventionsrelates no a torque wrench.

' objectofmyiinvention is to provide'a torqueiwrench which-willapplywtorque to aizllut)OIJOlZhfil.;SlIl1llfl1Ti'dCS/i06 by zrneans z-ofv a suitable: driving'zmotonaandiwhereby a certain :member iusing. an magneticn fluidarrangement is interposed :between lihGTmOtOF. and the'wrench unitritself toscausexslippage' whenxthemut .isatightene'd to a predetermined :torque.

A further: objectz'of. my; invention is toztprovide .aigeare ing arrangement in assooiationmwitlrrtheiwrench.fornincreasing zthe; torquer atzthe wrench rend.

vA:further;:objectaofmy. invention is to provide .azcertain sealingcdevice:which-zwill allow the;escapefofiheatedrgases developediin the magnetic fluid:.-portion 10f; thetdevice, :and yet willa-notsallowr the :sescape: oi) the: magnetic'fluid. :itself, and which devicei'will automatically; 'reasealthe; :unit after the-hot gases; have escaped.

'With thesezandi otherobjects 'in' view; my; invention :consists in: the construction, arrangemeng; land: combination of the various :zparts ofgmy...device;.-:whereby the objects contemplatedrare 'attaineduzas hereinafter more fully' set forth; t pointed; :out win my: :claims; and: illustrated- (1 11 the accompanying rdrawings uin which:

Figure :1 :is a ;side. (elevation aofiuthe torque Wrench .with the magnetic fluid.-drive:;portion;aszwellt as the:gear zdrive. portion. being: shown: I H CYOSSJSECiZiOH,

Figure 2 isarsectionalnview taken .along-:=.thei:lines -2"'2 of Figure .1-, and

Figure 3; is a schematic-:view of; the :electrical 1 circuit.

My: invention contemplates: the: provision. of a .torque wrench in which the. principle of-themagneticafiuidi drive isrtemployed, smthat' after tthewwrenchrperformsx the .operation f :tightening" the ..:nut:: to. a -pre.-set-:torque,z .the wrench .portion :will: ceaseeits rotation without: aiieeting the ..:;driving: motorgnan d :contemplates tprincipally :the furtherz'provision ofiana' arrangement; for 5 increasing the torque tmthexnutzaengaging :portion of 1 the .zdevice, and also the. provision of: :anztautomatic. sealing s. device .which will provide for the-"escape; of heated gases :developed' by the unit, ,:and :withranrinstant:rersealing. of therunitrwhen the device is 5 at rest.

The present application :is a: continuation'iin iparti of my fur-thenrapplication relating torMagnetic .Fluid Variable Torque Wrenches, Serial No. 244 956, filedwSeptem-. her 4', 5.195 1', :and relates: .to: certain; members-thereon.

.I: have: usedsther character 510 to designate amen-magneticatcasing' including; the {forward zend 'lPOlIlOIl 11 l in which is secured-gthesbear-ingz memberl;12; rwhich shearing memberreceivesthe shaft; 13 including the; squared: ipor-g.

tion 14 for engagement with the socket 15, which socket is to be use'd fortightening-the nut; and=suitably-attached at 16 to the casing jl0- is the'non-magnetic handle 17.

Attached to the inner end of the shaft 13 is an enlarged gear Z18fwhich meshes with a substantially smaller. gear 19,..the. gear 19 being att'achedto. a shaft 20'iwhich. is journaled 'wjthin'the bearingtzl}. the..shaft 20 extending intonthe snort-magnetic shaft portion,.22,1this shaft being engaged by means of a suitable sealing ring 23. The shaft 22 is journaled inthe bearing 24" which is secured within theztmagnetic 'hub1;25 ;;whichrextendse intorzthesdisk portion 26, the portion 26 being threadably .attachedr at which member 29" is secured as at 30 to the nonmagnetic shaft 31 of a-suitable-airmotor'32*Which--can be threadably engaged at 33- With "the adapter member "34'whicli is non-magnetic'and is secured at 35 1 to the casinglt).

Suitably secured to -the member 29 -is a further-magnetic member 36 and-positioned-between the member-"'29 and 36- is' an electro-rnagnetic coil 37. "Attachedtd-the periphery of the member -36 is a non-magneticringfis to whichis secured the innerspacers'39; and secured between.

the spacers 39-are=the annular'flat-disks"40-rwhich'extend inwardly-and are spaced from the inner spacers 41"Whi6h are secured to the extension 42 of-the-shaft"22;and" attached' between"the spacers 41-are the further annular flat'disks 43 which are correspondingly carried by the shaft 42, itbeingnotedthat-the various dislrs-"'40and-43 arespaced a slight distance apart. -A=nut= 44 is threadably engaged with the shaft portion 42 to securethis assembly, and-the" casing provided-between the member-'26 'and -the member36 is filled-substantially to'-the*'level"'45 with a magnetic fluid-"which"magnetic-fluid is preferably composed of 'oil having' finelydivided--magnetic=particles such as iron, suspended therein. The member'36- includes an'extending hub 'port-ion 46 "having the cavity "47 in which-cavityis' placed"an elastic neoprenedislef48ehaving the transverse -slit"" 49 therein; the disk 48 being secured by means-of the ring 50.

Attached to the member29 is a-'-disk'51 which is made of a suitable non-conductingmaterial in whichmember 51 are secured-the annular conducting rings '52- which 7 contact the brushe's-53-and-54,- these brushes beingyconnected by-means of' suitable -leadsshown to a twin-lead 55 Which'passes to a voltage control' box-su'ch as a variabletransformer56-(seeFigure 3), the lead to the brush"54'-passingto a';contact57 which is adapted, to

' contact thefurthercontact'SSiWhen the lever59 is pulled by means ofthe finger'grip'portion 60,'the various-brushes, contacts; *etcz, --being suitably insulated.

The. air motor32 includes'the'handle" 61 secured thereto; both=ha'ndles"17 'and161 being used when'the'tool is employed fortightening, nuts andthelike', it being .understoo'dthatxthe handle'17'for instance can be placed at any position desired.

.In .using the device, the air motor 32 will rotate con-' stantly,l thereby driving the. member '29; the member 51,

as well astheaportions 28,16, an'd25, and the fiat annular' disks40'. When themember (it) is pulled by the operator, contact will .be established between. the contact members 57 and 58 which will correspondingly energize. the coil 37 which'will energize .the magnetic circuit which throughthefluid andthe disks,.so that as aresult, the

rotation-of the members 28 etc.,-will therebycausethe disks 43. to rotate;...ther eby rotatin thershaftr.portions..42 and..22 .Which .inaturnwill rotate the small :gear; 19, to

. thereby rotate the larger. gear 18 .andtsupplyingtorque toatheshaft-13 for-rotating the nut engaging member 15. As-soon as the nut is tightened. to a pre-set .torque,.slippage will, occurbetween theudisksnand fluid so that;.the motor.'32 can -still-,;ro,tatewithouttinjury. Thetpre set torque, can; be;determine d-by. regulating the voltage,;.=and

it Will also be noted that the torque is multiplied through the gear arrangement at ztr-diminished'speed.

. I, have.;fonnd;-.that thesmagnetic fluid duringzthearapid rotatioma'ndi-slippageof :the:.disks; :Will becomesheatedto adegree:whereim-gasestwill"form;and;without:1he;use of the neoprene disk 48, these gases would escape past the sealing member 23 and into the bearings etc., causing harmful effects. However, by means of the slit 49 in the disk 48, during operation these gases upon expanding will force through the slit 49 which will open slightly to permit escape thereof, thereby relieving the pressure on the sealing member 23, and when the unit is not operating, the resilient nature of the neoprene member will cause the slit to close tightly again preventing waste of the magnetic fluid. During rotation of the tool, the magnetic fluid will be centrifugally urged outwardly thereby filling the entire annular space, forming a hollow pocket as indicated by the dotted line character 62 and the fluid will then be spaced from the neoprene disk, and it should be specifically understood that disks of other material could be used as well, neoprene being preferred since it is oil resistant.

It will now be noted that l have provided the various advantages mentioned in the objects of my invention with other advantages being readily apparent.

Some changes may be made in the construction and arrangement of the parts of my invention without departing from the real spirit and purpose of my invention, and it is my intention to cover by my claims any modified forms of structure or use of mechanical equivalents which may be reasonably included within their scope.

I claim as my invention:

1. A variable torque wrench comprising a driven shaft, a casing attached to said shaft, said casing containing a magnetic fluid therein, said casing further including magnetic portions, a further shaft rotatable in said casing, magnetic disks attached to said further shaft whereby rotation of said casing will cause a binding magnetic action between said magnetic casing portions and said disks to thereby rotate said further shaft, means for electrically energizing said casing magnetic portions including a coil wound in said casing, means for electrically energizing said coil including an electric circuit passing thereto, a switch in said circuit whereby the magnetic circuit can be broken when desired, one end of said casing having an aperture therein, a resilient member secured across said aperture, said resilient member including a lengthened slit to provide means for causing escape of hot gases caused by the heat effects generated in said casing during rotation and slippage of said disks, and whereby said slit will re-seal said resilient member to retain said magnetic fluid when said wrench is in an inoperative condition.

2. A variable torque wrench comprising a driven shaft, a casing attached to said shaft, said casing containing a magnetic fluid therein, said casing further including magnetic portions, a further shaft rotatable in said casing, magnetic disks attached to said further shaft whereby rotation of said casing will cause a binding magnetic action between said magnetic casing portions and said disks to thereby rotate said further shaft, means for electrically energizing said casing magnetic portions including a coil wound in said casing, means for electrically energizing said coil including an electric circuit passing thereto, a switch in said circuit whereby the magnetic circuit can be broken when desired, one end of said casing having an aperture therein, a resilient member secured across said aperture, said resilient member including a lengthened slit to provide means for causing escape of hot gases caused by the heat effects generated in said casing during rotation and slippage of said disks, and whereby said slit will re-seal said resilient member to retain said magnetic fluid when said wrench is in an inoperative condition, said aperture and said resilient disk being positioned substantially along the longitudinal axis of said further shaft.

3. A variable torque wrench comprising a driven shaft, a casing attached to said shaft, said casing containing a magnetic fluid therein, said casing further including magnetic portions, a further shaft rotatable in said casing,

magnetic disks attached to said further shaft whereby rotation of said casing will cause a binding magnetic action between said magnetic casing portions and said disks to thereby rotate said further shaft, means for electrically energizing said casing magnetic portions including a coil wound in said casing, means for electrically energizing said coil including an electric circuit passing thereto, a switch in said circuit whereby the magnetic circuit can be broken when desired, one end of said casing having an aperture therein, a resilient member secured across said aperture, said resilient member including a lengthened slit to provide means for causing escape of hot gases caused by the heat effects generated in said casing during rotation and slippage of said disks, and whereby said slit will re-seal said resilient member to retain said magnetic fluid When said wrench is in an inoperative condition, said aperture and said resilient disk being positioned substantially along the longitudinal axis of said further shaft, an outer stationary casing enclosing said casing, means for increasing the torque of said further shaft including a small gear attached to said further shaft, :1 larger gear meshing with said small gear, a still further shaft attached to said larger gear, a nut engaging member attached to said still further shaft.

4. A variable torque wrench comprising a driven shaft, a casing attached to said shaft, said casing containing a magnetic fluid therein, said casing further including magnetic portions, a further shaft rotatable in said casing,

annular members attached to said further shaft whereby rotation of said casing will cause a binding magnetic action between said magnetic casing portions and said annular members to thereby rotate said further shaft, means for electrically energizing said casing magnetic portions including a coil wound in said casing, means for electrically energizing said coil including an electric circuit passing thereto, a switch in said circuit whereby the magnetic circuit can be broken when desired, one end of said casing having an aperture therein, a resilient member secured across said aperture, said resilient member including a lengthened slit to provide means for causing escape of hot gases caused by the heat effects generated in said casing during rotation and slippage of said annular members, and whereby said slit will re-seal said resilient member to retain said magnetic fluid when said wrench is in an inoperative condition.

5. A variable torque wrench comprising a driven shaft, a casing attached to said shaft, said casing containing a magnetic fluid therein, said casing further including magnetic portions, a further shaft rotatable in said casing, magnetic disks attached to said further shaft whereby rotation of said casing will cause a binding magnetic action between said magnetic casing portions and said disks to thereby rotate said further shaft, means for electrically energizing said casing magnetic portions including a coil wound in said casing, means for electrically energizing said coil including an electric circuit passing thereto, a switch in said circuit whereby the magnetic circuit can be broken when desired, an outer stationary casing enclosing said casing, means for increasing the torque of said further shaft including a small gear attached to said further shaft, a larger gear meshing with said small gear, a still further shaft attached to said larger gear, a nut-engaging member attached to said still further shaft.

References Cited in the file of this patent 

